Breakdown of collagen in cartilage, bone, ligaments and tendons is an important component of the destructive/proliferative lesion in rheumatoid arthritis. In response to chronic synovial inflammation, collagenase in latent form is released from synovial cells; latent enzyme can bind to collagen fibrils, is activated by proteinases, and initiates collagenolysis. We plan to define the intracellular events accompanying the induction of collagenase in human and rabbit synovial cells in response to phorbol myristate acetate (PMA). Adherent cell populations from matrix free synovial samples carried through less than or equal to eight passages, and established cell lines produced by ionizing radiation of monolayer cultures will be used. Phospholipid turnover in cell membranes and details of arachidonic acid metabolism will be correlated with time course and quantities of collagenase and neutral proteinase release. To make possible intracellular localization studies of collagenase in monolayer cultures and of both intracellular and extracellular localization of enzyme and specific inhibitor of collagenase (It) in human tendon, collagenase and It will be purified and monospecific antibody to them produced by conventional and hybridoma techniques. Localization using ferritin-labeled antibodies will be combined with functional assays for collagenase. Use of monensin, a monovalent ionophore which can prevent release of latent collagenase from cells, will facilitate these studies. Retinoic acid and its analogues in low concentrations (10 to the minus sixth power M) appear to inhibit collagenase production by synovial cells in vitro. We propose to use this compound as a prototype drug for possible use in pharmacologic suppression of the destructive-proliferative lesion in chronic arthritis. Definition of the effects of these compounds on cell functions (e.g., protein and nucleic acid synthesis, proliferative capacity, non-collagenase enzyme production) will be followed by in vivo studies in rats with streptococcal cell wall-induced arthritis and type II collagen-induced arthritis.